JPS63106501A - Method for detecting groove position - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a welding position detection method for detecting a groove position using a light cut image obtained by irradiating a slit light onto a groove area to be welded. Regarding.

[Conventional technology]

As a method for detecting the groove position, a slit light is irradiated onto the groove surface of the welding material, thereby obtaining a light-cut image that crosses the groove, and this light-cut image is captured by an imaging device. There is a method in which the optical section image obtained by the method is processed by an image processing device to detect the groove position. Such a technique is generally called a groove position detection method using optical cutting. Note that there are 1 documents related to the groove position detection method using the optical cutting method, for example, Japanese Patent Application Laid-open No. 56-1362.
There is a publication No. 80.

[Problem that the invention seeks to solve]

The groove position detection method using the optical cutting method as described above inputs the optical cutting image as an image and processes this image, so if the input image is not appropriate, the groove position can be detected accurately. This becomes difficult. In other words, the reflected image when the slit light is irradiated onto the welding groove is the workpiece material 1.
Not only does it vary greatly due to changes in the state of the surface finish, but it also varies greatly due to changes in the relative posture between the groove surface and the detection unit. For this reason, even if the image signal can be input optimally in a certain situation, if there are changes such as those described above, the input image signal will become inappropriate for detecting the groove position, and the groove position may not be detected accurately. also occurs.

In order to eliminate such problems, the threshold value when digitizing the analog image signal obtained by the imaging device is floated to improve the S/N ratio, but this is not sufficient. In particular, if the difference between the 7 degree level of the reflected light from the part irradiated with the slit light and the brightness level of the part not irradiated with the slit light is small, it is difficult to obtain an image sufficient for detection. If the amount of irradiation light of the slit light is made too large, not only the part irradiated with the slit light but also the surrounding area will be illuminated, making it difficult to accurately detect the groove position.

An object of the present invention is to provide a groove position detection method that can accurately detect the groove position even when the material or surface condition of the workpiece changes or the attitude of the detection unit changes.

[Means for solving problems]

The above purpose is to first evaluate the light sectioned image of the groove area obtained when irradiating the slit light with an arbitrary light intensity, and to determine whether the light sectioned image at this time is suitable for detecting the groove position. If it is inappropriate, the amount of light of the slit light is adjusted depending on the difference between the state of the light-cut image and the expected optimum state.

This can be achieved by inputting the optically sectioned image again after the adjustment and detecting the groove position by processing the inputted optically sectioned image again.

[Effect]

Even when the material of the workpiece changes, the surface processing condition changes, or the posture of the detection unit changes, first irradiate the slit light with a desired light intensity (for example, the light intensity at the previous detection), and then Since the optically cut image is input and processed to determine whether it is suitable for detecting the groove position, the groove position will not be detected in an inappropriate state.

In addition, if the result of this judgment is that it is inappropriate, check how much and how the input light section image deviates from the optimal state, and adjust the slit light to be irradiated according to the degree or type of deviation. Adjust the light intensity. Then, a photocutting image obtained by the slit light irradiation after this adjustment is captured, a more appropriate photocutting image is obtained, and the groove position is detected. Therefore, even if there are changes as described above, the groove position can always be detected stably and accurately.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 8. FIG. 1 is a schematic configuration diagram of a groove position detection device according to an embodiment of the present invention. In the figure, 1 is a welding torch, 2 is a welding wire, and 3 is a welding torch.

Welding groove surfaces of weld base materials 4 and 5 (hereinafter simply referred to as grooves)
This is an irradiation optical system that irradiates slit light 7 onto 6 portions.

Reference numeral 8 denotes an observation optical system such as an ITV that observes (images) a light cutting line 9 obtained when the groove 6 is irradiated with the slit light 7 from above the welding base materials 4 and 5. The welding torch 1, the irradiation optical system 3, and the observation optical system 8 are integrally arranged, and are freely movable over the groove 6 by moving the welding torch position control mechanism 10 lψ.

FIG. 11 shows an image processing device that is composed of the following parts. That is, 12 is an image input/output unit that A/D converts the analog Na signal obtained by the observation optical system 8 into a digital quantity and outputs image data to each part in the image processing device 11, and 13 is λ data for both groups. an image storage unit for storing 1
Reference numeral 4 denotes a calculation unit that calculates the optimum irradiation light amount and the tracing position of the groove 6, the details of which will be described later. Reference numeral 15 denotes external equipment such as an irradiation optical system drive circuit 17 and a welding torch position control circuit 18, which will be described later. A control section 16 is a main control section that comprehensively controls each of the above-mentioned sections 12 to 15.

A method for detecting a groove position in an embodiment of the present invention will be described with reference to FIGS. 2 to 8.

FIG. 2 is a flowchart illustrating the groove position detection method of the present invention, taking as an example the case where the groove shape is a lap joint shown in FIG. 1. Hereinafter, the groove detection procedure will be explained according to the second same flowchart.

As shown in FIG. 2, first step F1) is to irradiate the groove surface with the slit light of an arbitrary light Jit (indicated as In).
The light-cut image 9 is input (step F2), and the density pattern (distribution) of the obtained light-cut image of the groove surface is
It is detected which attribute of density patterns prepared in advance is classified (step F3).

Here, the above-mentioned step F11. The optical section image obtained in F2 is classified as to whether or not the groove position can be detected correctly. FIGS. 3A and 3B show a method of classifying the density patterns.

Square sides ABCD in FIG. 3A are image data including a groove light cutting line obtained by the observation optical system 8.

9a is a light cut image that appears brighter than the background 9b. The line segments HI Hz and Hz Ha of the light section image 98 are the first
The optically sectioned iFr images of the upper surface and end surface of the welding base material 5 in the figure are shown, respectively, and the line segment Hs Lz is the optically sectioned image of the upper surface of the welding base material 4 in the same figure. The u and v coordinate axes in FIG. 3A indicate the horizontal and vertical axes of the observation optical system 8, respectively. Adding the density values of each pixel in the horizontal direction from the image data in FIG. 3A,
FIG. 3B shows an example in which this is calculated for each pixel in the vertical direction and expressed as a density distribution in the vertical direction. From this calculation result, as shown in the figure, the maximum value Bmax of the concentration (addition value)
*Calculate the minimum value B SIn and the intermediate value Bay between the two.

In the detection of the density pattern in step F3 of FIG. 2, the above-mentioned BmaXyBm*n and Bav are used as parameters. That is, the obtained image data is determined depending on whether both equations (1) and (2) are satisfied. Determine whether the image allows accurate detection of the groove position.

B-ax B-tn< B w
・= (1) Brt< B at< B ding!
...(2) Formula (1)
B, and BTI and Btz in equation (2) are concentration addition values determined empirically or logically.

Equation (1) detects whether the difference between the bright and dark parts of the light sectioned image falls within a predetermined tolerance value (B,'I), and equation (2) It is detected whether the brightness is within the range of the upper limit (BTU) and lower limit (Btt).

In step F4 of FIG. 2, it is determined whether or not equation 1 (1) and equation (2) are simultaneously satisfied. When both equations 6 and 6 are satisfied, the process advances to step F5 and step Fl.

A desired groove tracing position is calculated from the optical cutting image data that has been previously input and stored in F2.

If at least one of formula (1) and formula (2) is not satisfied in step F4, the material and surface condition of the weld base metal, the detection unit consisting of the irradiation optical system and the 11 side optical system, and the weld base metal It is determined that an appropriate groove light cutting image has not been obtained due to changes in the relative orientation of the groove, etc., and the process branches to step F6.

In step F6, the properties of the density pattern of the light-cut image are further classified into three types, and three methods are used to detect the groove position by controlling the irradiation light amount of the irradiation optical system 3 according to the properties of each density pattern. Branch to one of the following steps.

The first method is a case where formula (1) is satisfied but formula (2) is not satisfied, and Bav≧BT! Or, when Bay≦BTL, that is, when the light-cut image is too bright or too dark as a whole, a war is made. In this case, the process branches to step F7 to calculate the optimum condition for the amount of irradiation light. Fourth
6 to 6 show a method for calculating the optimum irradiation light amount of the irradiation optical system in step F7.

In FIG. 4, square sides ABCD are image data including a groove light cutting image obtained by the M measuring optical system 8, similar to FIG. 3A. In the figure, points Vl to Vy1 in the vertical axis V direction
The density of the light cut image 9a in each horizontal line is examined. Figures 5A and 5B are examples of the measurement, and each horizontal
3. In the former measurement example, the density of the light-cut image on the line is within the sensitivity of the light-receiving element (not shown) of the a-measuring optical system 8, and when it exceeds the sensitivity, the light-cut Image 9
Find the peak value 1 of the concentration corresponding to a.

In the case of the latter measurement example, the width Bz of the portion where the density is saturated is calculated. In this way, the horizontal line v
After obtaining A or B1 indicating the density of the light sectioned image 9a in each line from 1 to vn, n pieces of data are averaged to calculate a representative value of the brightness of the light sectioned image 9a. Next, from the representative value of the brightness of the light sectioned image 9a, it is determined that the brightness of the light sectioned image is the maximum density of the light receiving section of the observation optical system 8, which is 1. &8
The set value of the irradiation light amount of the irradiation optical system 3 that will be in the vicinity is calculated backwards. Once such an appropriate amount of irradiation light has been determined, step F8 in FIG. F9. After FIO processing is performed, the groove position is detected by irradiating the slit light again. In other words, when the brightness of the light-cut image is low as shown in Figure 5A, or when the density of the light-cut image is high as shown in Figure 5B. As shown in Fig. 5C, the amount of irradiation of the second slit light is controlled so that the dynamic range of the light receiving section is effectively used for imaging.As a result, a clear light sectioned image can be obtained. Highly accurate detection of groove position deviation is possible in image processing.

FIG. 6 shows another embodiment of step F6 in FIG. 2 described above. In FIG. 6, square sides abcd are areas for calculating the representative value of brightness of the light-cut image 9a. The calculation method is the same as described above, but the calculation time is reduced by narrowing the calculation area.

Next, the second step shown in steps Fil to F14 in FIG.
The slit light amount control method will be described using FIGS. 7A to 7D. In this case, the targeted groove light cutting image is a 0 local strong reflection image, which is a case where formula (1) is not satisfied and a local strong reflection image such as at the corner of the groove does not occur. For groove images in which a
The groove detection is performed according to the flowchart of 8. In this case, an image is generated in which the brightness of each line segment of the light section image is partially different.

In FIGS. 7A to 7D, the same parts as in FIGS. 3A and 3B are indicated by the same symbols. In the examples shown in FIGS. 7A and 7B, the difference between Bsax and B m I n, that is, the brightness fluctuation is large.

In addition, the brightness of the light cut image is the line segment H1)Iz,)T2-H
Assuming that the allowable value B tx t B Tz that can be accurately image-processed and shown in equation (2) that changes on each surface of the welding base material shown by a * Hs Ll is also shown in the same figure, Each line segment becomes undetectable. For this reason, in step F1,1, first, the V of the boundary part of each line segment is
For example, 0 to detect the approximate position.

The integrated value of the horizontal line in Figure 7B is calculated in the vertical direction of the light receiving screen (
V), peak values (two locations) appear at the boundary as shown in Figure 7C, so this peak position (Figure 7C)
+, vz).

Furthermore, for each of the three line segments separated at the boundary, representative values of the brightness of the line elements are calculated using the same method as shown in FIGS. 3A and 3B. Then, the set value of the irradiation light amount of the irradiation optical system 3 is calculated so that the brightness of each of the three-element light section images is close to the maximum density I m&X of the light receiving section of the observation optical system 8. Step F12. F
In step F13, the operation of irradiating appropriate slit light for each line segment of each cut image and inputting and storing the groove image is repeated.Furthermore, in step F14, each line image information obtained above is combined into one image. The groove images are combined and the groove position is detected.

As a result, the brightness of the optically sectioned image is partially affected by changes in light reflectance due to the material and surface finish of the groove surface, and changes in the incident angle of light due to differences in the relative posture of the detection unit and the groove surface. Accurate detection is possible even when the characteristics are different.

Next, the third step shown in steps F15 to F18 in FIG.
The slit light amount control method will be explained using FIG. 8A and FIG. 8B. In this case, the target groove light cutting image is one in which a locally strong reflection image occurs. In the example of the groove surface of the lap joint shown in FIG. 1, the above-mentioned locally strong reflection image is likely to occur at the corner portion of the weld base material 5.

Figures 8A and 8B show an example of a light section image that is subject to the third slit light amount control. In Figure 0, the same parts as in Figures 3A and 3B are indicated by the same symbols. Ta. Similar to the images that are subject to the second slit light amount control shown in FIGS. 7A to 7D, B, □ and B +++in
The difference between Bmax and Bmin, that is, the brightness fluctuation of the cut image, is large. Both are similar in this respect, but in step F6 of Fig. 2, it is calculated whether the difference between Bmax and Bmin exceeds a certain value (Bp). However, if it exceeds Bp, it is determined that a locally strong reflected image is included in the optically sectioned image, and the groove position is detected according to the third slit light amount control method described below.

In step F15, first, the representative values of the brightness of the line segments of the three elements of the light sectioned image are calculated in the same manner as in step F6, and the brightness of the light sectioned image of these three elements is determined by @measuring optical system 8.
The setting value of the irradiation light amount of the irradiation optical system 3 that will be in the vicinity of the maximum concentration Iwax of the light receiving section is calculated backward. next,
After calculating the brightness of the corner portion of the light sectioned image shown by B waax in FIG. 8B, the setting value of the irradiation light amount of the irradiation optical system 3 is calculated backward in the same manner as described above. Step F16. F17
Then, the appropriate slit light is irradiated for each line segment and local area of each cut image, and the groove image is input and stored.Furthermore, in step F18, the image information of each line segment and local area is combined into one image. Combined with the groove image.

Detect the groove position.

This makes it possible to accurately detect the groove position even if the brightness of the light-cut image differs locally or greatly changes locally.

〔Effect of the invention〕

Even if the reflected light when the slit light is irradiated onto the welding groove changes depending on the material of the workpiece or the processing finish of the surface, or depending on the relative posture of the groove surface and the detection part, the present invention can be applied. According to the method, after evaluating the photo-cutting image that has been captured once, the photo-cutting image can be detected by irradiating the appropriately controlled slit light again, so the accuracy can always be maintained without being affected by the changes in the groove detection conditions mentioned above. This has the effect of enabling accurate detection of the groove position.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram according to an embodiment of the present invention. FIG. 2 is a diagram showing the operation flow of the embodiment of FIG. 1, and FIG.
3B and 3B are diagrams for explaining a method for classifying density patterns of light-cut images, FIG. 4 is a diagram for explaining a method for calculating density patterns from light-cut images, and FIGS. 5A-5
FIG. 5C is a diagram showing an example of a density pattern, FIG. 6 is a diagram for explaining a method of calculating a density pattern from a light-cut image, and FIGS. 7A to 7D are diagrams showing density patterns for each line segment of a light-cut image. Figure 8A for explaining concentration detection methods in different cases
This figure and FIG. 8B are diagrams showing a light-cut image in which the density locally changes and its density pattern. DESCRIPTION OF SYMBOLS 1... Welding torch, 2... Welding wire, 3... Optical system for irradiation, 6... Groove surface, 7... Slit light, 8
... Observation optical system, 9... Optical cutting line, 10... Welding torch position control mechanism, 11... Image processing device, 12
...Image input/output section, 13...Image storage section, 14...
- Arithmetic unit, 15... External device control unit, 16... Main control unit, 17... Irradiation optical system drive circuit, 18... Welding torch position control circuit.

Claims (1)

[Claims] 1. A light cut image is input by irradiating a groove to be welded with slit light and capturing an image of the irradiated groove portion, and the light cut image is processed. In the groove position detection method of detecting the groove position by first irradiating the slit light with an arbitrary light intensity and inputting a light cutting image, the input light cutting image is used to detect the groove position. If it is inappropriate, the amount of light of the slit light is adjusted according to the difference between the state of the light cutting image and the expected optimal state, and after the adjustment, the light cutting is performed again. A groove position detection method characterized by detecting a groove position by input processing an image.